板形环受热变形有限元分析及理论计算研究

应用热/结构直接耦合有限元方法对压磁式板形测量仪中的板形环受热后的温度场分布及热变形进行了仿真分析,并进行了理论计算对仿真结果进行了校验,所得结果可以预知板形环的安装孔在受热后的变形量,在板形环结构设计时就可以给出相应的配合尺寸补偿值,保证在工作温度变化后仍具有优良的配合,对压电磁板形测量仪的设计及安装调试都具有重要的实际指导意义。

L形包角环口板加强方钢管T形节点轴向滞回性能研究

为研究L形包角环口板加强方钢管T形节点(LCPT)轴向滞回性能,对一组包角环口板加强T形节点进行轴向往复加载试验,并与未加强(URT)和覆板加强节点(DPT)进行对比。结果表明:包角环口板加强节点的轴向滞回性能较优,LCPT试件比URT试件的最大荷载可提高103.2%;LCPT试件比DPT试件的累积耗能能力更好,且LCPT试件比DPT试件的拉压对等性更好。进一步对包角环口板尺寸和屈服强度进行有限元参数分析,结果表明:包角环口板厚度是影响LCPT节点轴向滞回性能的关键几何参数,提高包角环口板屈服强度可提高节点承载力,但对节点耗能能力几乎无影响。最后,对比覆板、环口板、包角环口板三种方钢管加强节点的承载和耗能机理,包角环口板加强节点的轴向滞回性能更优。

基于人工智能算法的空气轴承式板形仪检测辊环优化设计研究

针对空气轴承式板形仪检测辊环的结构参数优化问题求解的复杂性,提出了采用基于神经网络的模拟退火遗传算法的智能优化方法。对板形仪检测辊环结构参数优化的神经网络基本结构、遗传算法个体与适应度函数的构造、遗传算子的设计及参数选取等进行了深入的研究,并结合工程实践有效验证了该算法的有效性。

环口板加强T形管节点抗冲击性能机理研究

为深入研究环口板加强后T形管节点的抗冲击性能,文章采用试验研究和有限元研究相结合的方法,对未加强和环口板加强T形管节点的抗冲击性能进行了比较研究,旨在确定环口板加强节点受冲击后的典型破坏模态;并通过对变形发展、局部变形和整体变形的区分、冲击力-位移关系曲线、能量耗散等分析,揭示环口板加强节点的抗冲击工作机理,研究环口板的局部加强作用,确定环口板加强方式的有效性,可为管结构抗冲击设计和加固维护提供参考。

T形钢管混凝土柱-混凝土梁外加强环板式节点抗震性能正交试验研究

对18个T形钢管混凝土柱-混凝土梁外加强环板式节点采用有限元与正交试验法相结合的方式进行抗震性能研究。结果表明,节点的裂缝发展经历初裂、通裂、极限、破坏四个过程;牛腿在梁端荷载的传递过程中起到桥梁作用;最终以牛腿与梁交界处形成塑性铰而破坏,符合"强节点弱构件"的抗震设计思想。对节点极限承载力、位移延性系数以及能量耗散系数三个性能指标影响最为显著的因素均为框架梁配筋率。框架梁混凝土强度等级的提高可以提高节点极限承载力,但是增幅过大不利于节点抗震性能,所以工程设计时应合理地选择框架梁混凝土强度等级。

T形钢管混凝土柱-混凝土梁外加强环板式节点抗震性能非线性分析

通过ABAQUS软件对15个T形钢管混凝土柱-混凝土梁外加强环板式节点抗震性能进行非线性分析。结果表明,节点模型均在核心区产生应力集中,不过参数的变化导致应力集中以及向四周扩散的程度有所差异。各节点模型的滞回曲线形状饱满,没有捏缩现象,滞回性能良好;位移延性系数均大于1.93,等效粘滞阻尼系数均大于0.180,能量耗散系数均大于1.134,这些抗震性能指标远远超过普通钢筋混凝土结构的要求,部分甚至超过型钢混凝土结构的要求。通过参数分析,了解节点抗震性能指标随参数的变化规律。框架梁配筋率增大不仅可以提高节点承载能力,而且对节点抗震性能提高也很有帮助;牛腿长度增大虽对节点承载力能力较为有利,但对抗震性能影响比较有限。

Three-dimensional analysis of a thick FGM rectangular plate in thermal environment

The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional elasticity. Noticing many FGMs may have temperature-dependent properties, the material constants were further considered as functions of temperature. A solution method based on state-space formulations with a laminate approximate model was proposed. For a thin plate, the method was clarified by comparison with the thin plate theory. The influences of material inhomogeneity and temperature-dependent characteristics were finally discussed through numerical examples.

Free vibration of piezoelectric annular plate

General solutions for coupled three dimensional equations of piezoelectric media were used in this work to obtain some analytical solutions for free vibration of piezoelectric annular plates. These solutions not only satisfy the governing equations at every point in the concerned region but also satisfy the prescribed boundary conditions at every point on the boundaries. Therefore, they are three-dimensional exact. Numerical results are finally tabulated.

Method of closed loop springback compensation for incremental sheet forming process

The closed loop control model was built up for compensating the springback and enhancing the work piece precision.A coupled closed loop algorithm and a finite element method were developed to simulate and correct the springback of incremental sheet forming.A three-dimensional finite element model was established for simulation of springback in incremental sheet forming process.The closed loop algorithm of trajectory profile for the incremental sheet forming based on the wavelet transform combined with fast Fourier transform was constructed.The profile of processing tool path of shallow dishing with spherical surface was designed on the basis of the profile correction algorithm.The result shows that the algorithm can predict an ideal profile of processing track,and the springback error of incremental sheet forming is eliminated effectively.It has good convergence efficiency,and can improve the workpiece dimensional accuracy greatly.

Numerical modeling of seismic behavior of ellipse and peanut-shaped auxetic steel plate shear walls

This study proposes a new auxetic-shaped steel plate shear walls(simply referred to as ASSPSWs)consisting of boundary members and built-in perforated infill plates.The connection type between the boundary members is a hinge joint.The hole forms on the infill plates include orthogonal ellipse-shaped(ASSPSW-OE)and orthogonal peanutshaped(ASSPSW-OP).This paper studied the hysteretic performance of two steel plate shear walls’types based on the finite element analysis method.Within the study context,a parametric analysis was carried out to investigate the influence of various factors,such as hole size and hole distance,on the seismic performance of steel plate shear walls(SPSWs).The results indicated that reducing the the ratio of the ligament thickness to ellipse major axis(t/D)in orthogonal ellipse-shaped SPSWs can effectively increase the porosity while reducing the bearing and energy dissipation capacities.Under the condition with the t/D unchanged,increasing the ratio of the major to minor axis of the ellipse(d/D)raises the porosity and does not significantly reduce the bearing capacity and energy dissipation capacity of the SPSWs.For orthogonal peanut-shaped SPSWs,the holes’geometrical parameters significantly influence the hysteretic performance.Particularly,with the increase in the radial ratio of large to small circles in a peanut-shaped hole(R/r),the spacing between cells decreases.When drift exceeds 2%,the equivalent viscous damping ratio decreases sharply.Unlike the orthogonal ellipse-shaped SPSWs,changing the arrangement angle of peanut-shaped cells has no significant effect on orthogonal peanut-shaped SPSWs.However,the larger the angle,the greater the out-of-plane buckling of orthogonal ellipse-shaped SPSWs;thus,the energy dissipation capacity is reduced.The similarities lie in that the larger cell arrangement angle will make the steel plates have a complete stress field,and the bearing capacity will be slightly improved.When the cell arrangement angle(θ)is 45°,the SPSWs can develop high initial stiffness.

Postbuckling behavior of 3D braided rectangular plates subjected to uniaxial compression and transverse loads in thermal environments

Postbuckling behavior of the 3D braided rectangular plates subjected to uniaxial compression combined with transverse loads in thermal environments is presented.Based on a micro-macro-mechanical model,a 3D braided composite may be treated as a cell system and the geometry of each cell is deeply dependent on its position in the cross-section of the plate.The material properties of the epoxy are expressed as a linear function of temperature.Uniform,linear and nonlinear temperature distributions through the thickness are involved.The lateral pressure(three types of transverse loads,i.e.transverse uniform load;transverse patch load over a central area;and transverse sinusoidal load)is first converted into an initial deflection and the initial geometric imperfection of the plate is taken into account.The governing equations are based on Reddy’s higher-order shear deformation plate theory with a von Kármán-type of kinematic nonlinearity.Two cases of the in-plane boundary conditions are also taken into account.A perturbation technique is employed to determine buckling loads and postbuckling equilibrium paths of simply supported 3D braided rectangular plates.The results reveal that the temperature rise,geometric parameter,fiber volume fraction,braiding angle,the character of the in-plane boundary conditions and different types of initial transverse loads have a significant effect on the buckling and postbuckling behavior of the braided composite plates.

Study on coupled vibration characteristics of a cylindrical container with multiple elastic annular baffles

The coupled vibration characteristics of multiple elastic annular baffles of the same inner radius in a partially liquid-filled rigid cylindrical container were studied. The liquid domain was divided into several simple sub-domains so that the liquid velocity potential in each liquid sub-domain was of class C 1 with continuous boundary conditions. Based on the superposition principle, the general solution of the liquid velocity potential corresponding to each liquid sub-domain was obtained by means of the method of separation of variables. The coupled modes of the multiple elastic annular baffles were expressed in terms of dry-modal functions. The free surface condition, the interface conditions and coupled vibration conditions were expressed in terms of Fourier series along the liquid height and Bessel series in the radial direction, respectively. Stable and fast numerical computations were investigated by the convergence study. Excellent agreements have been achieved in the comparison of re- suits obtained by the proposed approach with those given by the finite element software ADINA. The natural frequencies and mode shapes versus the position, the inner radius and the number of the annular baffles were thoroughly discussed.

A dislocation-based model for cyclic plastic response of lath martensitic steels

Softening behavior of lath martensitic steels is related to the coarsening of laths and dislocation evolution during cyclic deformation.Involving the physical mechanism,we developed a dislocation-based model to study the cyclic plastic response for lath martensitic steels.For a block,we proposed an interfacial dislocation evolution model to physically present the interaction between mobile dislocations in the block and interfacial dislocations by considering the coarsening mechanism of the laths.Moreover,the evolution behavior of backstress caused by dislocation pile up at the block boundary has been considered.Then,a hierarchical model based on the elastic-viscoplastic self-consistent(EVPSC)theory is developed,which can realize the scale transition among representative volume element(RVE),prior austenite grains(PAGs)and blocks.According to the proposed model,the effective mechanical responses including the cyclic hysteretic loop and peak stress at different cycles for lath martensitic steel have been theoretically predicted and investigated.